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Author Topic: Covering undercambered wings is it easy?  (Read 688 times)
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bbdave
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« on: June 13, 2019, 03:50:24 PM »

How easy is it to cover undercambered wings what's the best technique with tissue?.

Dave
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skyraider
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« Reply #1 on: June 13, 2019, 04:09:45 PM »

I use a mini roller to apply the adhesive then apply the tissue. Use care as you
don't want to have any pulling on missed spots. Better to be a little loose than
tight. Just my way on how I do mine. Haven't had an issue yet ( knock on wood ).
What subject are you working on?

Skyraider
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edhardin
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« Reply #2 on: June 13, 2019, 04:37:59 PM »

I use Elmers white glue thinned with a little water, brush on and do two or three bays at a time.
Press gently over each rib with your finger. After wing is completely covered let dry over night
before shrinking with a light water spray.
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bbdave
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« Reply #3 on: June 13, 2019, 05:33:38 PM »

Thanks guys I'll give it a go.

Dave
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duration
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« Reply #4 on: June 13, 2019, 07:09:13 PM »

Dave,

Always cover the bottom first. That gives you access from the top so you can brush some dope along the lower sides of ribs for better adhesion. Be sure to check that tissue is adhered full length of every rib---push lightly or blow from top.

If you are using dope as adhesive, it helps to brush a coat on bottom edge of rib and lit dry, then lightly sand with very fine sandpaper, and brush on a second coat. This gives the tissue a better "grab" when you apply.

Louis
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ZK-AUD
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« Reply #5 on: June 13, 2019, 11:19:26 PM »

gluestick works well but let it dry properly before shrinking - I also make a simple jig to hold the top of the wing straight while applying the undercambered bottom covering or you can really lock in some twists you don't want!
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billdennis747
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« Reply #6 on: June 14, 2019, 03:16:34 AM »

There are few sounds in aeromodelling that are more depressing than the 'ping' of tissue pulling away from undercamber as the dope dries. I cover the bottom first and run a line of dope inside the rib with a fine brush to make sure it sticks.
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DavidJP
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« Reply #7 on: June 14, 2019, 05:01:51 AM »

Haven't used a mini roller but otherwise do much as has been said - including Bills running a fine brush with dope down the line o the rib before covering.  And so far have not had the "ping" of pulling away.  I find too that shrinking the tissue beforehand is not that critical if you have been reasonably careful in pulling it tight as the dope seems to work quite well (50-50). 
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billdennis747
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« Reply #8 on: June 14, 2019, 05:12:03 AM »

running a fine brush with dope down the line o the rib before covering.
No, after covering the bottom
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Starduster
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« Reply #9 on: June 14, 2019, 08:11:26 AM »

Many years ago, the now-defunct (as least as far as I can tell) company "Aerodyne" had a Covering Adhesive product. You would paint the stuff on your frame, let dry and then lay the covering material on the frame and with a small brush, just run acetone along the frame. the stuff stuck instantly. The only draw-back was that it was fairly heavy, but for under-camber wings it was amazing.

Anybody remember this stuff? Any idea what was in it? I'm thinking it was nitrate dope and Super Seam, but I don't know for sure.
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« Reply #10 on: June 14, 2019, 11:10:36 AM »

I think it partly depends on the covering material being used. Dope works well on absorbent tissue like Modelspan, but for less absorbent tissue, e.g. Esaki, I use wallpaper paste, mixed to a non-runny consistency and brushed onto the structure. The water content softens the tissue and ensures good adhesion. Just take care not to over-wet it when water shrinking.

Don
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faif2d
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« Reply #11 on: June 14, 2019, 12:48:33 PM »

Charlie Sotich from The Illinois model aero club was my mentor years ago.  He told me to mix some acetone based glue into nitrate dope about 50/50 and use that to attach paper to undercamber ribs.  It did work rather well!
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bbdave
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« Reply #12 on: June 14, 2019, 02:46:47 PM »

Wow lots here to try out I will start a build thread then ask the question again on that when I'm ready to cover it will be a KK Senator and as I'm not sure what the kit tissue will be like it will be even more relevant then.

Dave
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danmellor
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« Reply #13 on: June 14, 2019, 03:49:30 PM »

A decent tissue paste is your friend...

Dan.
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billdennis747
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« Reply #14 on: June 14, 2019, 04:29:23 PM »

I'm not sure what the kit tissue will be like
It'll be ok but white. Suggest you get some coloured Esaki light tissue from Flitehook
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Big G
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« Reply #15 on: June 14, 2019, 05:28:53 PM »

As the late, great John O'Donnell explained to me one time, as we were walking back from a long retrieve, there is only one way to cover FF wings, undersurfaces especially, and that is with DOPE. Forget tissue paste and anything else.

Using a fine brush, apply unthinned clear dope to the edge of each rib and spar and TE and LE of the under-cambered wing. Allow to dry. No need to sand. Lay the tissue on DRY. Can be Jap or Modelspan, makes no difference. The big 'secret' is to start at the centre of everything. Using dope thinners, run it along the lower spar (if there is one) first; press down lightly with finger to ensure contact.
Work outwards from the middle to the tip and centre-section. Then again starting from the middle of the wing, run thinners along the rear edge of each rib, again pressing down lightly with finger. Repeat with front edge of ribs. Then apply thinners to the TE, again from the middle of the wing outwards. After which, the LE. Providing the paper is ironed and flat, there is no need to pull it tight as you go along. Remove excess paper at TE, LE and tip with fine wet-and-dry. Cover the top of the wing in the same way, but trim the tissue so there is an overlap of approx 3mm at the TE, LE and tip. Wet the overlap (the tongue is the best way!) then using thinned dope fold it over to make a neat joint. When everything is dry and settled, spray lightly with water to shrink, pinning or weighing the wing down as the water dries.

I have tried tissue-paste, and it's a waste of time, as is any other type of paste. Dope is the way to do it.

G
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DerekMc
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« Reply #16 on: June 14, 2019, 06:26:50 PM »

there is only one way to cover FF wings, undersurfaces especially, and that is with DOPE. Forget tissue paste and anything else.

I guess all those planes I have aren't FF then, or maybe it's just the wings? Then again I didn't use DOPE to attach the covering on the other parts either. Definitely not FF Roll Eyes I wonder what they are?  Grin

Yes, there are several ways to attach tissue to undercambered wings as this thread clearly shows.
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« Reply #17 on: June 14, 2019, 06:35:34 PM »

I beg to disagree.  I've been covering undercambers  for 70+ years and used nothing but various types of paste; initially the products marketed by KeilKraft, Joyplane,  etc.. later Britfix, Humbrol ... when that went out of production I  turned to wallpaper 'lap and seam' paste with equally satisfying results.

Easy and quick to apply, no adhesion problems when water shrinking or doping. No time wasted applying coats of dope/thinners to airframes and associated drying times, sanding between, etc.; I feel I could have a structure covered in the time it took an equivalent to be prepared with dope.

As always.. each to their own....  but a definitive statement such as the last line of Big G's message is erroneous and misleading.

Jim
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DerekMc
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« Reply #18 on: June 14, 2019, 06:43:26 PM »

As always.. each to their own....  but a definitive statement such as the last line of Big G's message is erroneous and misleading.

Jim

Exactly!
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Derek
Mike Thomas
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« Reply #19 on: June 14, 2019, 07:29:47 PM »

An advantage of the dope and thinners method is that it is relatively easy to remove tissue when repairing or recovering. Just brush acetone or thinners over the places where the tissue is attached, and it will come away cleanly.
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Big G
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« Reply #20 on: June 15, 2019, 07:41:26 AM »

Yes indeed, each to their own - and discussions concerning the tissue-covering of wings nearly always lead to disagreements and 'my way is the best way', and all that. But believe me, I was building FF models from the age of about 8 onwards, and hearing JO'D's method od dope + thinners was an absolute revelation when I first tried it. My late FF friend Ray Monks also used this method, and it there was anyone who knew all about building and covering FF models it was he. The last line of my post is by no means erroneous and misleading - it is how I do it because it's the best way that I have found. So carry on with whatever method you feel is best for you, and I hope your under-cambered wings don't gradually lose their covering....

And incidentally the dope + thinners method works (for me, that is...) just as well for Jap as it does for Modelspan.

G
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« Reply #21 on: June 15, 2019, 12:37:50 PM »

Ouch Big G!

Sorry but I have to call you out on the one!  You can’t say what you said essentially this “MUST” be they way it is done and condemn other ways completely and then suddenly say “each to their own”

PVA (essentially the lap and seam paste) sticks tissue down like sh*t to a blanket, and so I have to also disagree.  Not been at this as long as applehoney (sorry mate my dad is only 72!) but I can tell you it doesn’t come off - which is fact it’s biggest problem as you have to get it right first time.  The advantage being of course that you don’t get as high as kite doing it (although some like the effect I can’t say I am big fan!

BUT dope and thinners is better for repairs and removing it if things go a bit pear shaped, and great if you want to get... ahem... a bit light headed from time to time...  Grin

Andrew
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Buster11
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« Reply #22 on: June 15, 2019, 01:54:29 PM »

My ten cents-worth. I've always stuck undercamber with dope, or at least ever since I found that using thinned PVA made it impossible to remove covering when I wanted to. Usually a thin strip of rib came away along with the tissue or else a nasty strip of PVA remained on the rib to mar the re-covering job.
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« Reply #23 on: June 15, 2019, 02:48:34 PM »

All;

The dope vs paste seems to be a US vs British thing. Growing up in the US, I had never heard of attaching tissue with anything other than dope. (Ok, banana oil was mentioned in one model building book from the 1930s---but that stuff is just better-smelling dope.)

The first I remember hearing of using paste was in Aeromodeller. Lots of good free flight ideas in that magazine but, at least for me, paste wasn't one of them. The whole idea reminded me of the horrible library paste we had to use in grade school.

Louis
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lincoln
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« Reply #24 on: June 15, 2019, 04:26:14 PM »

I heard of using Elmers glue, thinned with water, decades ago.

Personally, I like using Fab-Tac or Sig Stix it, same methods as with dope. For dope, I'd prefer dope for full scale. All three are stickier than the regular model airplane dope I've tried.  Or Uhu Stick for indoors. However, I haven't done many concave surfaces.
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